Supplement lubricant free pneumatic motor

ABSTRACT

The present invention provides a pneumatic motor having a motor body having an air inlet and an air outlet, at least one rotor mounted in a chamber of the motor body and adapted to be driven by compressed air fed into the air inlet and an adhesive lubricant applied to the at least one rotor, the lubricant being sufficiently adhesive to remain substantially adhered to the at least one rotor under operational speeds in excess of 13500 rpm.

TECHNICAL FIELD

The present invention relates to a pneumatic motor. The invention hasbeen developed primarily for use in underground mining and tunnellingtools, such as a roofbolter, and will be described hereinafter withreference to this application. However, it will be appreciated that theinvention is not limited to this particular field of use. Otherapplications include motors for processing equipment in the food andpharmaceutical industry, in which contamination-free process equipmentis required.

BACKGROUND OF THE INVENTION

Pneumatic motors use rotors driven by compressed air and are common inpower tools and other machinery. Pneumatic motors using very clean anddry air can be operated without supplementary lubrication. However, mostpneumatic motors require supplementary lubrication to function reliablywith durability. The supplementary lubrication is fed into thecompressed air stream by a controlled drip rate of oil relative to thesupplied airflow. All the components exposed to the compressed air arethen coated with a film of oil.

In mining and construction, pneumatic motors rely more heavily on thesupplementary lubrication to combat compressed air that can be highlycontaminated with contaminants such as water, rock and coal. Without thesupplementary lubrication, corrosion and fouling of internal componentscan render the equipment inoperable in a short time.

The lubricators which feed oil into the airflow are generally unreliableand often result in too little or too much oil being fed in. As notedabove, lack of oil feed will reduce the operational life of theequipment. Excessive oiling reduces the performance of the equipment dueto the sludging of internal components. Excessive oiling can also renderthe equipment inoperable.

The responsibility for maintaining oil supply to the lubricatorsgenerally falls to the operators, who, in practice, rarely check thelubricator oil level and often operate equipment without sufficient oil.A lubricator without sufficient oil can also act as a water trap whichresults in water being fed into the air stream and the misconceptionthat the lubricator is full of oil.

Further, equipment with motors having supplementary lubrication expel afine mist of oil with their exhausted air. This can be detrimental tothe health of operators who inhale the contaminated air and creates apotential occupational health and safety liability.

OBJECT OF THE INVENTION

It is the object of the present invention to substantially overcome orat least ameliorate one or more of the disadvantages of the prior art,or to provide a useful alternative.

SUMMARY OF THE INVENTION

Accordingly, the present invention provides a pneumatic motor having:

a motor body having an air inlet and an air outlet;

at least one rotor mounted in a chamber of the motor body and adapted tobe driven by compressed air fed into the air inlet; and

an adhesive lubricant applied to the at least one rotor, the lubricantbeing sufficiently adhesive to remain substantially adhered to the atleast one rotor under operational speeds in excess of 13500 rpm.

Preferably, the at least one rotor includes a drive rotor and an idlerrotor. Further preferably, the rotors are mounted on sealed cage deepgroove ball bearings.

In a preferred embodiment, the motor body is constructed from corrosionresistant material. Preferably, the motor further includes a reductiongearbox having a gearbox body constructed from a corrosion resistantmaterial. Preferably, the corrosion resistant material comprises nylon,stainless steel or acetyl resin engineering plastic.

In an optional embodiment, the motor is adapted for bidirectionalrotation and the air inlet and air outlet are selectivelyinterchangeable.

In a preferred embodiment, the motor body includes internal bafflingformed in the motor body and associated with the air outlet, thebaffling being adapted to muffle motor noise. Preferably, the motor bodycomprises a wall surrounding the chamber and the baffling is provided ina conduit formed within the wall, the conduit providing fluidcommunication between the chamber and the air outlet. Furtherpreferably, the baffling is provided by the conduit following acorrugated path within the wall. Optionally, the conduit extends aroundthe wall, substantially circumventing the chamber.

Preferably, the adhesive lubricant is Optimol Paste White T Spray (trademark), marketed by Castrol.

BRIEF DESCRIPTION OF THE DRAWINGS

A preferred embodiment of the invention will now be described, by way ofexample only, with reference to the accompanying drawings wherein:

FIG. 1 is a side view of an embodiment of a motor according to theinvention;

FIG. 2 is a front view of the motor depicted in FIG. 1;

FIG. 3 is an open top view of the motor of FIG. 1;

FIG. 4 is a perspective view of the motor of FIG. 1, showing internaldetail; and

FIG. 5 is a top view of the motor of FIG. 4.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

Referring to the drawings, FIGS. 1 to 5 depict an embodiment of a motor10 according to the present invention. The motor 10 comprises a motorbody 12, having an air inlet 14 and an air outlet 16. The motor body 12has a chamber 15 in fluid communication with the air inlet 14 and airoutlet 16. The chamber 15 houses a steel alloy drive rotor 18 on a driveshaft 20 and a steel alloy idler rotor 22, intermeshed with the driverotor 18, on an idler shaft 24. Each shaft 20, 24 is mounted on sealedcage deep groove ball bearings (not shown). A conduit 25 extends from anopening 26 to the air outlet 16. The conduit 25 is formed within thewall of the motor body 12, extending around the periphery of the chamber15 and following a corrugated path.

During construction of the motor 10, the rotors 18, 22 are sprayed withan adhesive lubricant such as Optimol Paste White T Spray (trade mark)marketed by Castrol. The lubricant is sufficiently adhesive to remainadhered to the rotors 18, 22 under operational speeds in excess of 13500rpm.

In operation, compressed air is fed into the air inlet 14. Since theintermeshed rotors 18, 22 prevent air passing between the rotors 18, 22,the air is forced around the periphery of the rotors 18, 22. As the airflows between the rotors 18, 22 and the wall of the motor body 12, theair drives the two rotors 18, 22 to rotate in the direction indicated bythe arrows.

The air then exits the chamber 15 via the opening 26 and flows along thecorrugated conduit 25 around the periphery of the chamber 15 beforebeing expelled via the air outlet 16. As the air travels along theconduit 25 noise energy is absorbed into the wall of the motor body 12and the noise output at the air outlet 16 is reduced.

Since the adhesive lubricant adheres to the rotors 18, 22 at normaloperational speeds, the motor 10 doesn't require supplementarylubrication. This results in cleaner exhaust, less maintenance and morereliable performance.

The motor body 12 is advantageously constructed from corrosion resistantmaterial such as nylon, stainless steel or acetyl resin engineeringplastic, such as polyoxymethylene. This construction provides a lightweight motor that is not susceptible to corrosion when used incontaminated environments.

The motor 10 can also be configured to operate selectively in forward orreverse, i.e. bidirectional rotation. When the motor is operated inreverse, the air inlet becomes the air outlet and vice versa. Thisfeature is particularly advantageous in applications of the motor in thefood and pharmaceutical industry.

Although the invention has been described with reference to a specificexample, it will be appreciated by those skilled in the art that theinvention may be embodied in other forms.

1. A pneumatic motor having: a motor body having an air inlet and an airoutlet; at least one rotor mounted in a chamber of said motor body andadapted to be driven by compressed air fed into said air inlet; and anadhesive lubricant applied to said at least one rotor, said lubricantbeing sufficiently adhesive to remain substantially adhered to said atleast one rotor under operational speeds in excess of 13500 rpm.
 2. Themotor of claim 1, wherein said at least one rotor includes a drive rotorand an idler rotor.
 3. The motor of claim 1, wherein said rotors aremounted on sealed cage deep groove ball bearings.
 4. The motor of claim1, wherein said motor body is constructed from corrosion resistantmaterial.
 5. The motor of claim 1, wherein said motor further includes areduction gearbox having a gearbox body constructed from corrosionresistant material.
 6. The motor of claim 4 wherein the corrosionresistant material comprises nylon, stainless steel or acetyl resinengineering plastic.
 7. The motor of claim 1, wherein the motor isadapted for bidirectional rotation and the air inlet and air outlet areselectively interchangeable.
 8. The motor of claim 1, wherein said motorbody includes internal baffling formed in said motor body and associatedwith said air outlet, said baffling being adapted to muffle motor noise.9. The motor of claim 8, wherein said motor body comprises a wallsurrounding said chamber and wherein said baffling is provided in aconduit formed o within said wall, said conduit providing fluidcommunication between said chamber and said air outlet.
 10. The motor ofclaim 9, wherein said baffling is provided by said conduit following acorrugated path within said wall.
 11. The motor of claim 9, wherein saidconduit extends around said wall, substantially circumventing saidchamber.
 12. The motor of claim 1, wherein the adhesive lubricant isOptimol Paste White T Spray (trade mark).